Electrical burglar-alarm.



No. 693,068. Patented Feb. u, |9o2.

H. c. a w. a. nooma.

ELECi'BlGAL BURGLAR ALARM.

(Application filed Mar. 24. 1899.)

' (No Model.)

Mi] 6, 56 Lzvenlbltc Nrrnn STATES ATENT OFFICE.

HENRY C. ROOME AND WILLIAM G. ROQME, OF JERSEY CITY, NE\V JERSEY.

ELECTRICAL BURGLAR-ALARM.

SPECIFICATION forming part of Letters Patent No. 693,068, dated February11, 1902.

Application filed March 24, 1899. Serial No. 710.298. on model.) I

To all whom, it 772100;] concern.-

Be it known that we, HENRY O. ROOME and WILLIAM G. RooME, of JerseyCity, county of Hudson, and State of New Jersey, have invented a new anduseful Improvement in Electrical Burglar-Alarms, of which the followingis a specification.

We will describe a burglar-alarm embodying our improvement and thenpoint out the novel features in the claims.

In the accompanying drawing, A designates a choke-coil. We may make thisby stamping up pieces of soft thin sheet-iron in the form of plates ordisks, with large holes in the center. On each piece of iron so treatedwill be a thin ring. The thinner it will be the better. \Ve japan orotherwise insulate the soft rings and place them one above another, soas to form a short cylinder. They may be riveted together with fiber orinsulated plugs or secured together in any other manner with insulatingmaterial. Around this cylinder are wound anumber of strandsofwire. Theaction of the iron in closed magnetic circuit makes an induced currentopposed to the current flowing in the turns of wire around thechoke-coil and the degree of choke or selfinduction may be regulated byincreasing or decreasing the number of turns of wire. The action of thechoke-coil can be Varied greatly by simply changing the frequency of thealterations of the current. Thus it will be seen we have a device in theguarded structure by means of which we can produce varying results onthe circuit by simply changing the frequency of the alternations at thecentral office, and these changes can be recorded on an alternatingmeasuring instrument at the central office.

To illustrate the value of this invention, suppose we were to measurethe resistance of the guarded structure just outside of the guardedstructure. If now we could sever the wires from the central officewithout giving an alarm and at the same moment connect them to aresistance coil or rheostat having a similar resistance to that of theguarded structure, the measuring instrument at the central office wouldbe widely deflected and the alarm given, as the action of theresistance-coil would be very different from the combined resistance ofthe resistance in the wiring and the choke-coil in the guardedstructure. Suppose we could now take the resistance-coil that we hadattempted to substitute and by adding iron to the center of it make achoke-coil out of it and keep adding iron until the needle of themeasuring instrument was returned to the proper position on thescale'.Itis onlynecessarynowthatthefre- 6o quency of the alternations bechanged at the central office. This may be accomplished by varying thespeed of the dynamo or by increasing or decreasing the number of polesin the field or armature, the two choke-coils havinga circuit than inthe artificial coil. It is noted that a portion of the resistance in theguarded structure consists of its protective wires, a portion being inthe signaling instrument and the balance in the choke-coil. Now as theyare not able on the outside of the guarded structure to separate thesetwo it follows that their choke-coil being the convolutions of all theresistance m ust require a difierent amount of iron than the regularchoke-coil, which has the resistance of the protective wires ahead ofit. Now when the frequency of the alternations at the central oflice ischanged the two choke-coils make a widely-different deflection in themeasuring instrument and the alarm is sounded. In fact, itis practicallyimpossible for any one to tamper with the circuit, as the alternationsare frequently changed at the central oflice and they would be detected.

We show a system whereby the normal resistance 0f the main line orguarded struco ture need not be changed or altered, and yet by means ofa transformer the deflection of the measuring instrument at the centraloffice can be changed at will without altering the resistance of theguarded circuit. There is also shown a simple ratchet-wheel device forchanging the strength of the circuit,which is controlled from thecentral oflice. The deflect-ion of the measuringinstrument may also bechanged without altering the resistance of IO the circuit by simplychanging the frequency of the alternations, the transformer or thechoke-coil producing a varied effect on their respective circuits whenthe frequency is changed.

C may represent the central office or place where the alarm is received.B B the guarded structure. The circuit may be traced from earth E bywire 1, collector-rings X of alternating-current generator or dynamoD,wire 2, and thence passing around a number ofcon- Volutions of thechoke-coil A, this coil being provided-With a finger a, which can bemoved so as to be connected with a greater orlesser number ofconvolutions of the choke-coil A; As'showu, the finger is so connectedthat the circuit coming from wire 2 must pass through two convolutionsof wire about the choke-coil before it connects with the movable fingera, thence by wire 3 to the alternating-current measuring or recordinginstrument G, here shown as an electrical measuringinstrument which'maybe similar in principle to a dynaniome-ter, such as described by EdwardWeston in his Patent No. 433,637, of August 5, 1890. Any desiredalternating recording instrument may, however, be used-in fact, a

double-relay system, one relay responding when the circuit is opened andadjusted to have its armature normally attracted and theother relayadapted to have its armature away from its magnet and only attractedwhenthe choke-coil A is shunted out ofcircuit. When the door A at theguarded structure is opened, the needle 72 of the recording instrument Gwill be caused to impinge against the contact a, closing its localalarm-circuit, the needle 72 being deflected away from this contact bythe tension of a hair-spring, which tends to throw the needle to theextreme left when there is no current flowing through its coils.

We prefer to make the scale-piece behind the needleofsomeinsulatingmaterialandcon tacts c and a movable and adjustable toany position on the scale. We show the head of a thumb-screw which maybe used to set them rigid in any desired position.

By simply increasing or decreasing the speed of the dynamo D andchanging the frequency of the alternations we can increase or decreasethe choking effect of the choke-coil A, located at the guardedstructure, and produce a deflection on the recording instrument as thecurrent is increased or decreased by the choking effects of thechoke-coil A. The needle n of the recording instrument G can now bebalanced and overcome the effects of the choke-coil A by moving thefinger a of the choke-coil A at the central office. This would producethe same effect on the recording instrument G as would be produced in acontinuous-current circuit by being able to decrease or increase theresistance in the guarded structure from the central office and at thesame time counteract the deflection of the needle at the central officeby giving more or less voltage, necessary to overcome the change, so asto hold sired point.

The generator or dynamo D is shown as a combination-dynamo. From theendmalternating current is taken from the collectorrings. From the end'y direct or continuous current is taken from a commutator.

The burglar-alarm circuit can be traced fromalternating-current-recording instrument G by wire 4', contacts 0 c ofpush-button F, wire 5, magnet k of the ratchet mechanism K, wire 6, bellK, wire 7, call-key L, wire 8, passing into therigid coil of thealternating-current relay N, coming out of this coilby wire 9 andpassing into the movable coil, coming out of the movable coil'by wire10, thence to the metal of the door-spring a the needle at any deof theattachment A through by wire 11,

coming out on the break spring a thence via wire 12 through thewiring-circuit, passing through the primary coil of the transformer I P,returning through the wiring-circuit by wire 13 to the tongue a of thedoor-spring a of attachment A andthence by wire 14 to earth at E. Theshunt-circuit wire 15 runs from wire 10 to contact-point 0 on the relayN. From the contact 0 a wire 16 extends to the earth E. This relay N issimilar to one described in a patent granted to William Maver, Jr., No.482,440, dated September 13, 1892, and is very similar in constructionand principle to the alternating'current relay G, being composed offixed and movable coils, without any iron or magnetic material, anddepends for its operation on the attraction of one coil for the othercoil, the coil to which the wire 8 is connected being a fixed andimmovable coil, and the other coil being pivoted and movable. A springat is combined with this coil formovingitin one direction and acts toseparate the contacts 0 0 The tension of this spring is sufficient sothat when the transformer P is in circuit the current is not strongenough to move the coil and close the contacts 0 0 When, however, thedoor A is opened and the wire is connected through the door-spring a tothe tongue a wire 14 to earth E, shunting out the transformer, thecurrent is now strong enough to move the movable coil of the relay N sothat the contacts 0 0 are closed, closing the shunt-circuit by wire 16to E.

Q is a condenser which acts to balance the inductance of the relay N byits capacity and to discharge into the relay N between each alternationof current. It serves to shorten the neutral or no-current momentbetween each alternation, its discharge being a practical alternation ofthe current, which-will act to come in just ahead of the regularalternation andwith the same polarity.

The wire 18 connects the condenser Q with one side of the relay at wire8 and the wire 17 with the other side of the relay at wire 10.

The secondary current of the transformer P has its circuit completed bywire 24, some of the convolutions of the choke-coil A, finger a of thechoke-coil A, and wire 25, returning to the secondary coil of thetransformer.

K is a ratchet mechanism adapted so that when its magnet k is energizedsuiliciently to overcome the tension of a spring k on the armature k itwill move down, and the pawl [e at the end of the armature will engageone of the ratchet-teeth on the ratchet-wheel k and advance it onetooth, turning the axle connected to it, and with itthe finger a of thechoke-coil A, moving this linger in successive steps from onecontact-point to another, each contact-point inserting in successionextra lengths of the convolutions around the chokecoil A into thesecondary circuit of the transformer P. When the full number of turnshave been inserted, the next movement of the finger to the nextcontact-point will act to cut out the choke-coil completely. The springm of the bell K is adjusted so that the armature of this bell willrespond only to a direct or continuous current of greater strength thanthe normal current. of the direct current from the end 3 of the dynamoD, which may be traced from E by wire 19 to one of the brushes of thecommutator on the end g of the dynamo D. From the other brush a wire 20extends to a resistance J, and thence by wire 21 to contact a of thebutton F. WVhen it is desired to ring the bell K at B B, the push-buttonF is pushed in until the contact 0 touches the contact 0 and the bell Kwill respond, its spring m being adjusted so that the bell will respondto the direct or continuous current through the resistance J. The springof the ratchet mechanism K is adjusted so that the armature it will notrespond to the direct current when the resistance J is in circuit. Tocause this magnet is to be sufficiently magnetized, a switch R isprovided at the central oflice, and by means of the wires 22 and 23 theresistance J can be shunted out. When the push-button F is pushed in sothat the contacts 0 and c are connected, the armature of the magnet 70of the ratchet device K will respond and advance the finger a one step,thus changing the choke-coil of the secondary circuit of the transformerP. The transformer secondary circuit will now take more or less currentfrom the primary circuit of the transformer by induction, and therecording instrument G will be deflected. To offset this deflection, thefrequency of the alternations at the dynamo D may be changed, or thefinger aon the choke-coilAat the central office may be shifted. It willthus be seen that we here show a method by means of which the standingor deflections of the recording instrument G may be changed at will fromthe central office without changing the resistance of the circuit. Theseare important points, as the systems now in use depend entirely on achange of resistance,which makes itrather difficult to keep thesignaling- This is secured by means bells and devices for changing theresistance in adjustment.

It will be observed that it makes no difference how many turns of thechoke-coil A are included in the secondary circuit of the transformer P.It does not change the resistance of the primary circuit oralarm-circuit, and when the armatures and springs of the instruments Kand K are once adjusted they will always work just the same if thedirect or continuous current supplied by the wire 2lis of constantstrength, and it makes no difference whether the whole choke-coil is inthe secondary circuit or whether it is shunted out of the secondarycircuit, the resistance of the primary circuit remains the same, andthus the shifting device produces no effect on the working of thearmatures of K and K, as it does not alter the resistance of the primarycircuit.

The choke-coil A may, if desired, be connected directly to the wires 12and 13 and the transformer P be dispensed with.

A specially-constructed magnet for alternating currents havinglaminated-iron cores may be used in place of the relay N. The condensermay also be used with such a magnet, if desired.

The bellK and ratchet mechanism K may be combined, if desired, into onemagnet with both armatures, or the armature of K may be used in additionto ring a bell and K dispensed with, as it would do no harm to have theratchet device shift the finger a every time a signal was given. I

Intermittent or pulsatory currents may be used instead of alternatingcurrents for the burglar alarm or signaling circuits. These would act onthe secondary circuit of the transformer P, producing an alternatingcurrent in thesecondary circuit,which would in turn bechoked by thechoke-coil A. This would act to affect any recording instrument thatmight be used in its place.

The collector-rings on the end so of the dynamo D may be dispensed withand a mechanism provided to give pulsating currents of the samepolarity.

The instrument K may be constructed to act similarly to the press-magnetof a stockprinter, and the alternationsbe made at O O mechanically, asin a stock-printing ticker system. To operate the magnet is of ratchetdevice K,it would only be necessary to stop the mechanical alternator atG O, which would act to send direct or continuous current into thecircuit, causing the magnet is to respond.

Our system may also apply to coverings for safes, vaults, &c.

We do not wish to confine ourselves to the use of the recordinginstruments shown, as other instruments might be used.

What we claim as new, and desire cure by Letters Patent, is-

1. In aburglar-alarm system, the combination of a circuit extendingbetween a central oflice and a guarded structure, a source at to se- IOOthe central oifice for sending a continuous and an alternating currentthrough the circuit and two sets of instruments at the guardedstructure, one responsive to the alternating current and the otherresponsive to the continuous current and adapted to change the strengthof the alternating current.

2. In a burglar-alarm, the combination of a circuit extending betweenthe office'and the guarded structure, a ratchet or movable device at theguarded structure controlled from the central oflice, a secondarycircuit at the guarded structure, and means in said secondary circuitfor changing the self-induction of the secondary circuit, said meansbeing controlled by the ratchet, substantially as specified.

3. In a burglar-alarm, the combination of the alternating-currentgenerator,energizing the circuit extending to the guarded structure, analarm instrument,atransformer,and aratchet or movable device in thesecondary circuit of the transformer controlled by the central oflice,and adapted to change the selfinduction ofthe circuit at the guardedstructure, substantially as specified.

- 4, In a burglar-alarm, the combination of the alternating-currentgenerator, the circuit extending to a guarded structure, an alarminstrument, a choke-coil. or inductive device, and a ratchet or movabledevice controlled bv the central office and adapted to change'theself-induction of the circuit at the guarded structure, substantially asspeci- HENRY C. ROOME.

WILLIAM G. ROOME.

Witnesses:

HS. 0. CLUTSAM, v P. S. MACLURE, GEORGE H. NEWKIRK, SARAH E. ROOME.

